*Sighs.*
Are people seriously still on this?
The Raikage won that fight.
Would he have been dead at the end? More than likely.
Let me raise a few points before hand:
- Sasuke did not have his complete Susanoo at this time. That came afterwards, in the fight against Danzo.
- The Raikage was shown to be able to easily break Susanoo's ribs.
- Amaterasu spreads to whatever it touches.
Seeing as Sasuke was on the ground, helpless save for his Susanoo's ribs, and the Raikage was coming down very quickly and with a great amount of force (velocity is the primary factor in Sasuke's death, so pay attention here), not only would the Raikage have killed Sasuke, Sasuke would have helped him do it.
Smashing through the bones, his velocity aided by gravity, A's leg would have been engulfed in the black fires of Amaterasu. However, Amaterasu is a moderately-slow burning flame, but quick to spread. A's led drop would have continued on, smashing into Sasuke's chest.
That, alone should kill him, as his ribcage would have caved into his vital organs. However, there's an additional factor - the Amaterasu on A's leg has now spread to Sasuke's chest. Now, not only is Sasuke mortally wounded, he's engulfed in his own black-flames, his "scare tactic" was a double-edged sword and has come back to haunt him.
Sasuke was well and surely dead, had Gaara not intervened. Can I say that A would have survived the ordeal? No, I can't. However, I can say without a doubt that Sasuke would have dead.
Sasuke put up a good fight, but A won it, it's as simple as that.